Science and Seismic Surveys
Posted August 25, 2014
Worth reading: this presentation on the facts about offshore seismic surveying from the U.S. Bureau of Ocean Energy Management (BOEM) in its August “Science Notes” newsletter. It’s prefaced by William Y. Brown, chief environmental officer for BOEM, who focuses on the public discussion that has followed the agency’s July announcement that it would allow safe seismic testing off portions of the Atlantic coast:
I wanted to take some time to clear up a few misperceptions about the bureau's decision and what it means. As a scientist who has spent a good part of my career working in non-governmental environmental organizations and in industry, I understand and appreciate advocacy. At the same time, I believe that everyone benefits by getting the facts right.
The presentation includes an FAQ section dealing with some of the advocacy surrounding seismic surveying, as well as a fact sheet that explains that testing is used to aid oil and natural gas development and other purposes and that existing Atlantic seismic data is more than 30 years old:
G&G (geological and geophysical) surveys covered by this decision are not used exclusively for oil and gas exploration. These surveys are also helpful in identifying sand used for restoration of our Nation’s beaches and barrier islands following severe weather events and for protecting coasts and wetlands from erosion. Seismic and geologic coring surveys also provide information that is vital to the siting and development of offshore renewable energy facilities. G&G surveys also help to advance fundamental scientific knowledge and are currently conducted in the Gulf of Mexico and in countries around the world.
Brown points out BOEM has partnered with academia and other experts to invest more than $50 million on protected species and noise-related research since 1998, including the effects of seismic surveying on marine mammals such as sperm whales. Even so, misconceptions continue – hence the BOEM Q&A. Some key points:
Safe seismic testing doesn’t harm marine animals
To date, there has been no documented scientific evidence of noise from air guns used in geological and geophysical (G&G) seismic activities adversely affecting marine animal populations or coastal communities. This technology has been used for more than 30 years around the world. It is still used in U.S. waters off of the Gulf of Mexico with no known detrimental impact to marine animal populations or to commercial fishing.
Noise from seismic air guns has been exaggerated
Scientists who specialize in acoustics confirm that sounds in water and sounds in air that have the same pressures have very different intensities (which is a measure of energy produced by the source) because the density of water is much greater than the density of air, and because the speed of sound in water is much greater than the speed of sound in air. For the same pressure, the higher density and higher speed make sound in water less intense than sound in air.
The agency says that while scientists don’t know precisely what various marine species experience during seismic testing, there are indications the impacts are fairly limited:
Many marine mammal species – but not the baleen whales including North Atlantic right whales – have reduced sensitivity to sound signals that are in the same frequency range as airplanes and air gun arrays. Some whales appear to move away from surveys, indicating that they probably don't like the noise, but bottlenose dolphins have often been observed swimming toward surveying vessels, and ride bow waves along the vessels.
Contrary to some claims, government scientists do not expect injuries and death to marine life
After a thorough, public process, the Department selected a preferred alternative that included the most restrictive mitigation measures that would allow surveys to take place. We expect survey operators to comply with our requirements and, if they do, seismic surveys should not cause any deaths or injuries to the hearing of marine mammal or sea turtles.
There’s more in the BOEM presentation, but the major thrust is that safe, carefully regulated seismic surveying hasn’t adversely affected marine life in the past and won’t in the future. That’s the science speaking. Assertions to the contrary are “wildly exaggerated and not supported by the evidence,” Brown says in a recent magazine interview. “The real question is whether [whales] are just hearing a noise and turning around, or whether it disrupts them in a way that makes them move away from food or disrupts breeding,” Brown says. “There's just no evidence that happens.”
Documented fact and sound science are the only proper foundation for regulating seismic surveying and for the actual conduct of tests that will produce invaluable information about the nature of America’s offshore energy reserves. That knowledge is critical to developing offshore oil and natural gas – and in the process creating jobs, generating economic growth and increasing our energy security.
About The Author
Mark Green joined API after a career in newspaper journalism, including 16 years as national editorial writer for The Oklahoman in the paper’s Washington bureau. Previously, Mark was a reporter, copy editor and sports editor at an assortment of newspapers. He earned his journalism degree from the University of Oklahoma and master’s in journalism and public affairs from American University. He and his wife Pamela have two grown children and six grandchildren.
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